1. Technical Field
The present disclosure relates to an emitter and, in particular, to an emitter employed with the carbon nanotubes and a method for manufacturing the same.
2. Description of the Related Art
Carbon nanotubes (CNTs) are widely used as field emitters for field emission displays (FEDs) and liquid crystal displays (LCDs). Such CNTs have good electron emission characteristics, and chemical and mechanical durability.
Conventional field emitters are typically micro tips made of a metal such as molybdenum (Mo). However, the life span of such a micro tip is shortened due to effects of atmospheric environment, such as non-uniform electric field, and the like. A somewhat viable alternative has been carbon nanotubes having a high aspect ratio, high durability, and high conductivity preferably adopted as field emitters.
In order to obtain a high current density from carbon nanotube emitters, carbon nanotubes must be uniformly distributed and arranged perpendicular to a substrate. The carbon nanotube emitters are generally grown from a substrate using a chemical vapor deposition (CVD). However, the carbon nanotubes formed by this process may be entangled with each other on the top thereof, which result in a poor morphology of CNTs and poor performance on emitting. Alternatively, the carbon nanotube emitters may also be manufactured by printing a paste obtained by combining carbon nanotubes with a resin to a substrate. This method is easier and less costly than CVD and thus preferred to CVD. However, the carbon nanotubes formed by this process are too dense to emit electrons effectively because of the strong screening effect generated between adjacent carbon nanotubes.
What is needed, therefore, is a carbon nanotube emitter and a method for manufacturing the same that can overcome the above-described shortcomings.